Suction-Activated Core Catcher for Unconsolidated Subsea Formations
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Solution Overview
Problem
Conventional rotary coring tools fail to effectively extract cores from unconsolidated and fragmented subterranean formations, particularly undersea, due to premature release of debris and inefficiency in retaining loose particles.
Innovation Solution
A coring apparatus with a telescoping tubular liner and flexible catcher fingers that shift to enclose the core, utilizing hydraulic suction to capture and retain the core within the tool, allowing for efficient extraction of unconsolidated formations like gravels and dense sands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring collet retainer is used to grip the core sample, then consolidated hard material can be retained effectively, but unconsolidated and fragmented particles are released prematurely
Solution Approach 1:
The core catcher uses a dynamic mechanism where flexible fingers can transition between open and closed states. During drilling, the fingers remain open to allow unconsolidated particles to enter the core chamber. Upon activation by the retainer mechanism, the fingers close to secure the core sample, adapting their state to different operational phases.
Solution Approach 2:
The core catcher employs flexible fingers that can deform and conform to the core sample geometry. These flexible elements are capable of elastic deformation to allow particle passage during drilling, then maintain a closed configuration to retain the core, providing both permeability and containment functions.
2Reliability
If a fully enclosing catcher is used to capture fine loose particles, then particle retention is improved, but the tool requires surface intervention and large diameter tools which are not feasible on subsea platforms
Solution Approach 1:
The retainer mechanism is self-activating through a trigger-based system that responds to changes in the drilling environment or operational parameters. The mechanism automatically transitions the core catcher from an open to closed state without requiring external surface intervention, enabling autonomous operation on subsea platforms.
Solution Approach 2:
The patent replaces complex mechanical retention systems with a simplified trigger-actuated mechanism. Instead of relying on large-diameter tools or complex surface-controlled systems, a compact mechanical trigger system activates the core catcher closure, reducing overall tool complexity and enabling subsea deployment.
3Ease of operation
If a spring collet retainer with large opening is used, then core entry is facilitated, but unconsolidated particles are released during retrieval
Solution Approach 1:
The core catcher transitions from an open configuration during core acquisition to a closed configuration during retrieval. The flexible fingers dynamically adjust their state based on operational requirements, maintaining an open structure to facilitate core entry, then closing to secure the core during the return journey.
Solution Approach 2:
The retainer mechanism is pre-configured in an open state that allows free core entry during drilling operations. The trigger mechanism is pre-positioned to activate closure at the appropriate moment, ensuring the core is secured before retrieval begins, preventing particle loss during the return trip.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus ensures secure capture and retrieval of cores from unconsolidated formations by maintaining the core within the tool, preventing premature release and allowing for remote operation on subsea platforms.
Implementation Method 1
the disclosed apparatus comprises a coring tool forming part of a unique drilling system capable of evacuating the fluid from the sealed drill string
Implementation Method 2
When the piston is displaced by the intentional injection of hydraulic fluid, the volume of the third chamber expands, consequently withdrawing drilling fluid into the cylinder. As the drill string volume expands, the internal pressure drops, and the external pressure forces and shifts the internal mechanism to maintain equilibrium.
Implementation Method 3
The catcher may comprise an array of flexible fingers configured to lean centrally inward and exert a spring force to their natural position when elastically deformed outwards
Implementation Method 4
exert a spring force to their natural position when elastically deformed outwards, as in the preset position achieved by engagement with the telescoping, tubular liner
Data Source
AI summary
An apparatus for recovering a core from an undersea formation. A coring tool adapted for being connected to a drill string includes a coring bit for recovering the core from the undersea formation. A catcher has a closed state for sealing the core in the coring tool. A retainer retains the collapsible catcher in an open state, and an actuator applies suction to the coring tool. The applied suction serves to move the retainer to allow the catcher to collapse for capturing the core, such as by releasing flexible fingers of the core catcher from a telescoping liner associated with the retainer. Related methods are also disclosed.